For mobile electronic equipment including a mobile phone, a notebook size computer, a mobile cassette player, compact disc (CD) player, and mini disc (MD) player, dropping of the equipment is an ever-present danger when considering its intended use. Accordingly, protecting the equipment from impact caused by dropping the equipment has now been a growing need. A typical failure comes from distortion of a motherboard mounted on the equipment due to drop impact, by which some on-board components have shorts in the wiring, or come off the board. Therefore, to protect the equipment from such accidents, the following steps should be taken: i) selecting a material and a structure of electronic equipment to be tested; ii) determining a drop height and direction; iii) simulating drop impact acceleration applied to each section of the equipment; and then iv) getting feedback from the result and improving the design of the inner structure, for example, the position and method of installing a circuit board. However, the drop impact acceleration during falling greatly varies between different falling objects, and the acceleration applied to an object has significant consequence to the impact force. Furthermore, mechanical vibration and its corresponding frequency caused by the drop impact greatly depends on the structure of an object. The reasons above have been obstacles to detecting drop impact acceleration applied to a falling object.